1. Field of the Invention
The present invention relates to arc welding apparatus, and more particularly to TIG and to MIG welding apparatus wherein welding wire feeding speed and welding current may be selectably adjusted and controlled through a single point of activation such as a trigger attached to the welding torch handle. The present invention also provides a means for a welding torch operator to control the current, wire feeding speed, or both selectively from a location remote from the main current control and wire speed control through a single point of control by selecting the preferred variable parameter from a control on the welding torch.
2. Description of the Related Art
TIG welding is used for welding all types of metals in a wide variety of fields, such as manufacturing, ship building, pipe fitting or any other metal work. TIG welding techniques are well known, and typical apparatus uses a manual TIG torch wherein an arc is generated between the torch electrode and the base metal, and a welding wire is applied to feed material into the seam being welded during the welding operation. TIG welding techniques require the torch operator to hand feed wire material, presently most commonly available in 3/32″, ⅛″ and 5/32″ diameters. A typical welder may cut the wire into strips of approximately three feet so that the wire may be conveniently hand manipulated and not be of excessive weight or be of an unmanageable size.
Another common type of welding torch is a MIG torch which has an automatic wire feed mechanism wherein the wire also serves as the welding electrode or tip. The arc is generated between the automatically fed wire which protrudes through the center of the welding torch head and supports an arc between the wire and the object being welded. While such apparatus does provide for an automatic wire feed through the center gas cup of the torch, the apparatus is not portable, the welding torch head cannot be remotely located more than perhaps twenty-five feet from the welding machine or apparatus, and the MIG system provides other disadvantages.
Present TIG welding tools do not provide for an automatic or integrated application of welding wire to an existing TIG torch and torch handle, or for adjustability of the speed of the wire being fed to the head of the torch. Existing MIG types of welding equipment requires that the operator discontinue the welding operation and then adjust the rate of delivery of the material wire to a more suitable speed. Generally, this requires the operator to reach for a control panel which may or may not be located in close proximity to the work being performed.
Present equipment available today, which provides for automatic wire feed in a TIG torch operation, usually requires more than one operator, who must be specially trained, to operate large, expensive welding systems that cannot be adapted to any standard TIG torch or welding machine. An example of what may be found in the prior art is disclosed in U.S. Pat. No. 5,789,717, issued to Imaizumi et al for a Semi-Automatic TIG Welding Apparatus. This patent teaches an apparatus to feed welding wire to the vicinity of the arc tip of the welder and presents the wire material through the welder handle grip along with mechanisms to feed the other required supply lines as illustrated in the referenced patent. As is evident from the disclosure in Imaizumi, the welding wire feed mechanism is not adapted to be used with existing, conventional TIG touch handles. Imaizuni contemplates an integrated solution to the need for one handed TIG torch operation as is evident by the illustrations and the disclosure in said patent.
None of the equipment found in the existing art provides for a simple, portable means to automatically deliver wire to any standard TIG torch where the operator can continually adjust, regulate or otherwise control the feed speed of the wire being used in the welding process. The existing art does not provide for a simple means to adapt a TIG welding torch with a welding wire feed mechanism which is also capable of wire feed speed control and does not require altering or permanently modifying the existing torch to allow operation.
Both in MIG and TIG welding procedures, typically the current control mechanisms and the wire feed speed controls on a MIG apparatus are located away from the torch location in that the controls are typically mounted on the welding machine apparatus. Since such apparatus is typically located in a position remote from the welding job and the location of the actual torch and operator, it is not convenient to adjust the current controls or wire feed speed. There are welding devices which have taught the use of controls mounted on the welding torch to a limited extend such as the trigger mechanism and adjustable potentiometers mounted on the torch as shown in U.S. Pat. No. 5,595,671 issued to David.
There remains a need for a control system and means to allow the welding torch operator to selectively control either the current applied to the torch, the speed of the wire feed to the torch head, whether operating MIG or TIG apparatus, or both current and wire speed control through activation of a single control such as a trigger or foot petal located on or near the torch. Moreover, the need exists for providing such control in the welding process such that the welder operating the equipment can make such adjustments and control the indicated parameters while in the welding process without the need to stop welding to make the adjustments or return to the location of the welding machine to change parameters.